"Over the past decade, majorities have consistently said that 'occasional acts of terrorism in the U.S. will be part of life in the future.' This sentiment has spiked to 75% in the wake of the Boston bombings from 64% a year ago and now matches the previous high of 74% in 2003."

But Americans seem to be handling their fears. While a large majority think terrorism is a "part of life in the future," the percentage who say they are "very" worried about another attack has not gone up significantly: 23 percent, compared with 21 percent in November 2010. And the percentage who say they are "not too" worried about another attack or aren't worried at all stands at 41 percent, vs. 38 percent in November 2010. The remainder (35 percent now and 38 percent in November 2010) say they are "somewhat" worried.

Meanwhile, Americans are split on the question of whether there's much more authorities can do to keep the public safe:

"The national survey by the Pew Research Center, conducted April 18-21 among 1,002 adults, finds that the public is evenly divided over whether there is more the government can do to prevent attacks like the one in Boston: 49% say there is more the government can do to prevent such attacks, but nearly as many (45%) say there is not much more that can be done."

"Sixty three percent of Americans say they followed the story very closely, among the highest interest in any news story in the past decade. And the bombings drew far more public attention than any terrorist event since Sept. 11, 2001, which 78% reported following very closely in mid-October of that year."

Pew says each of its results has a margin of error of +/- 3.7 percentage points.